Unveiling Biodiversity: The Power of eDNA Analysis

Why is measuring biodiversity important?

Nature provides us with ‘ecosystem services’ (e.g., clean water, raw materials, carbon sequestration) which underpin healthy societies and economies. Biodiversity, which drives ecosystem function and resilience, is inherent to deriving these ecosystem benefits.

There is an estimated USD $700 billion funding gap for nature restoration. The development of biodiversity credits, alongside blue bonds and carbon credits, could be a potential financial tool to monetise the recovery of ecosystems. It is therefore essential that we are able to measure biodiversity with a certain degree of confidence, so Environmentalists, Scientists and Policymakers can understand how populations are changing over time and between habitats. But how can we measure biodiversity?

Until recently, measuring biodiversity would mean physically looking for flora and fauna and recording direct observations. This could involve visual surveys, trawls, seines and tissue biopsies. As well as being costly, time-consuming and invasive, these methods have obvious flaws when considering cryptic, rare or elusive species. Similarly, smaller organisms can be hard to identify in the field. So how can we measure what we cannot see?

What is eDNA?

Fortunately, as organisms move around their environment they are constantly shedding bits of themselves, in the form of dead skin cells, mucus and faeces. All of this organic matter contains DNA, known as environmental DNA (eDNA). Water, air, soil and sediment samples can be tested for the presence of eDNA, which indicates the recent presence of an organism in that environment, even if that organism has never been directly observed. This can be particularly significant if IUCN Red List species are captured in the samples, indicating the presence of threatened species. It can also notify the presence of invasive species, which are damaging to the ecosystem and commonly result in a loss of native biodiversity. Thus, eDNA analysis has allowed researchers to generate a much more robust and holistic picture of true biodiversity within an ecosystem, while also causing less environmental disturbance.

Figure 1. The benefits of eDNA as a tool to measure biodiversity (NatureMetrics, 2024)

Limitations of eDNA

eDNA has never been well characterised and does have its limitations as a tool. It can allow us to gather information on the presence or absence of a target species, but is unable to provide any information on factors such as species life stage, reproduction or fitness. However, DNA-based methods complement—rather than replace—traditional surveys. Methodologies such  as bioacoustics, satellites, cameras and LiDAR can be used in tandem with eDNA to broaden and deepen the evidence base.

Conclusion

eDNA has the potential to make significant contributions to the detection of invasive species, community and ecosystem biodiversity, functional diversity, wildlife, and conservation biology. As technology and ideas for the use of eDNA continue to develop, eDNA has the potential to continue opening up innovative and creative ways to study and help to protect the wildlife around us.